College of Science & Department of Physics Sitemap Search
BoxSand – Flip the Classroom

Free Body Diagrams: Nuts & Bolts

Free Body Diagrams: Nuts & Bolts

3. Nuts & Bolts

Algorithm

Expand

Other Algorithm Resources

Here is a 4 step process to setup FBDs:

Multiple Representations

Multiple Representations is the idea that a physical phenomena can be explored in many different ways. For example, there is the physical representation which models the system with figures and diagrams, such as a free body diagram. There is also the mathematical representation which uses the equation(s) governing the physics of the system. All of the representations can be used together to help us understand and quantify the physical phenomena.

Observe the different types of representations for this section below:

Physical Representation

Physical Representations explain the features of the situation in a visual way, often with vector representations of physical quantities overlaid a simple diagram or picture of the situation.

Mathematical Representation

Mathematical Representation uses equation(s) to describe the situation.

The main mathematical representation for forces will be applying Newton's Second Law to a physical problem. You will need to analyze the motion of an object and create a free body diagram of the relative forces in order to derive the force equations. We learned in the kinematics section how to analyze motion without any concern about the forces that caused the motion. The infographic below describes the relationship between force and accelertion. Thus, we may now analyze the forces acting on an object to determine the relative acceleration.

Page 3 of this site does a wonderful job of showing many of the different mathematical representations.

Graphical Representation

Graphical Representation describes the situation through use of plots and graphs.
 

Descriptive Representation

Descriptive Representation is made up enitrely of words or annotations. Think about how you might explain the situation to someone else.

This can be thought of as a word problem. For example, “If Steve pushes a one kilogram box for twelve seconds, and it goes five feet, how hard did Steve push?” would be a descriptive representation of a problem where you would have to translate a FBD into Newton's second law.

Actual Phenomena

Actual Phenomena could be thought of as doing the experiment.

Here is a video that descibes an actual situation with FBD techniques applied

Example Problems

Set 1: Net Force and Newton's Laws of Motion
Set 2: Drawing Free Body Diagrams

For additional practice and worked examples, visit the repository.